Conventionally, as described in, for example, Patent Literature 1, there is a vehicle door latch device including: a body accommodating therein an engagement mechanism, which restrains a door in a closed position by engaging with a striker on a vehicle body side; and a casing attached to the body and accommodating therein an operation mechanism, which has a locking and unlocking means that is able to switch over between an unlocked state where an engaged state of the engagement mechanism with the striker is releasable and a locked state where the engaged state is unreleasable. In this device, a waterproof seal, which is made of sponge or the like, soft, and band-shaped, is stuck onto a rear surface of the body, the rear surface of the body being above a striker advancing groove in the body and facing to an inner panel of the door, and onto a surface of a cover attached to the casing, the surface facing to the inner panel of the door, to prevent rainwater or the like that has gone inside the door from entering the striker advancing groove or the like from above.